Sill flashing is commonly used at the base of a building window to carry water draining from the window's framing system to the exterior of the building. The sill flashing is positioned beneath window framing, and end dams disposed at the ends of the sill flashing prevent water from draining from the side edges of the sill flashing into a building's wall cavity. FIG. 8 illustrates a conventional end dam and sill flashing assembly 800. Typically, the end dams 810 are L-shaped, having a horizontal portion 815 and a vertical portion 820, and are secured to the sill flashing 850 by engaging a threaded fastener 860 through the bottom of the sill flashing and into the horizontal portion 815 of the L-shaped end dam 810. To create a water tight seal, sealant is applied to the fastener holes 860 in the bottom of the sill flashing 850 and end dams 810 and between the ends of the flashing 850 and the vertical portion 820 of the end dams 810.
End dams affixed to sill flashing in this manner, however, are prone to leakage. The seals created at the holes through the sill flashing and end dams often break under the stresses of the window's assembly. In addition, the seals between the ends of the sill flashing and the end dams are relatively weak due to the lack supporting structure and are vulnerable to separation.
Accordingly, there is a need in the art for an improved sill flashing assembly that is more durable and water resistant.